Custom function context type helpers

[sbkl]

Having some hard time with these custom functions to get type helpers for the context of query, mutation and action.

import * as ConvexBase from "@/convex/_generated/server";
import {
  zCustomQueryBuilder,
  customCtx,
} from "zodvex";

// convex helpers trigger
export const triggers = new Triggers<DataModel>();

// convex helpers rls config
async function rlsRules(ctx: ConvexBase.QueryCtx) {
  const user = await getCurrentUserOrThrow(ctx);
  return {
    rules: {} satisfies Rules<ConvexBase.QueryCtx, DataModel>,
    user,
  };
}

// Helper to extract the convex ctx type from the custom functions
type CustomCtx<T> = T extends (config: infer Config) => any
  ? Config extends { handler: (ctx: infer Ctx, ...args: any[]) => any }
    ? Ctx
    : never
  : never;

// custom function
export const protectedQuery = zCustomQueryBuilder(
  ConvexBase.query,
  customCtx(async (ctx) => {
    const { rules, user } = await rlsRules(ctx);
    return {
      db: wrapDatabaseReader(ctx, ctx.db, rules),
      user,
    };
  })
);

// Works. I get the correct type
export type ProtectedQueryCtx = CustomCtx<typeof protectedQuery>;

But not for this custom mutation using triggers

import { Triggers } from "convex-helpers/server/triggers";
import {
  Rules,
  wrapDatabaseReader,
  wrapDatabaseWriter,
} from "convex-helpers/server/rowLevelSecurity";

// custom function wrapped with the triggers and rls config
export const protectedMutation = zCustomMutationBuilder(
  ConvexBase.mutation,
  customCtx(async (ctx) => {
    const withTriggersCtx = triggers.wrapDB(ctx);
    const { rules, user } = await rlsRules(withTriggersCtx);
    return {
      ...withTriggersCtx,
      db: wrapDatabaseWriter(withTriggersCtx, withTriggersCtx.db, rules),
      user,
    };
  })
);

// becomes any
export type ProtectedMutationCtx = CustomCtx<typeof protectedMutation>;

I think it is because the ctx in customCtx function is of type any to start with or maybe how the ctx merge is handled? If I remove the spread of the withTriggerCtx, the types go through properly. Any idea?

[panzacoder]

I need to look into Triggers more carefully, but this has been the case with most helpers from convex-helpers: the fundamental way that these functions infer types is not compatible directly with our zod interfaces, and we therefore have needed to recreate some of these helpers. See: my current PR for adding a zGetAll() helper #11

The problem is obviously that this is not sustainable, I can't just recreate the entire helpers library inside zodvex, so I need to find the right way to maintain this relationship.

I'll note that a new PR has been opened for updating convex-helpers with zod v4 compatibility, so it may be worthwhile checking there to see if a better solution has arisen. get-convex/convex-helpers#818

[panzacoder]

Hey! Scratch my last remarks 😂

Looks like this is working fine for me, but you need to give the ctx return from customCtx a hint

I'm not 100% sure why it works without adding it for the custom query, but if you update

export const protectedMutation = zCustomMutationBuilder(
  ConvexBase.mutation,
  customCtx(async (ctx) => {

to

export const protectedMutation = zCustomMutationBuilder(
  ConvexBase.mutation,
  customCtx(async (ctx: ConvexBase.MutationCtx) => {

The types should keep flowing just fine for you.

[panzacoder]

As a reference point, I do this with all of my custom builders, so it's actually good to know it can work without the extra type specification!

Reference: https://github.com/Motiion-Management/motiion/blob/main/packages/backend/convex/util.ts

[sbkl]

Hey! Scratch my last remarks 😂

Looks like this is working fine for me, but you need to give the ctx return from customCtx a hint

I'm not 100% sure why it works without adding it for the custom query, but if you update

export const protectedMutation = zCustomMutationBuilder(
ConvexBase.mutation,
customCtx(async (ctx) => {
to

export const protectedMutation = zCustomMutationBuilder(
ConvexBase.mutation,
customCtx(async (ctx: ConvexBase.MutationCtx) => {
The types should keep flowing just fine for you.

This did the trick. The CustomCtx now works as expected and helper functions can now receive the ctx and it all flows down. So the issue was that the custom builder function ctx was any. Adding the type just fixed it lol.

I have updated my repo with the convex.json file for the convex project to build properly (sorry about that) and updated with working examples. Now mutation with triggers and rls also work properly.

https://github.com/sbkl/zodvex-test

Maybe worth mentioning adding the type to the ctx of customCtx function would be helpful.

Awesome work on this library btw.